DESCRIPTION (applicant's abstract): Approximately 60 percent of B-cell lymphomas are characterized by the presence of the t(14;18) (q32;q21) chromosomal translocation. Diagnosis and post-treatment follow-up are currently performed by karyotype, Southern blotting, or PCR, which have problems with specificity and sensitivity. Fluorescence in situ hybridization (FISH) addresses these limitations; however, no clinically tested FISH probes are available for detecting the t(14; 18) translocation. Phase I research developed novel probes for interphase FISH analysis of the t(14; 18) translocation. Using both normal and tumor samples, high sensitivity and specificity of the probes were observed. Using tumor specimens from multiple tissue types, Phase II research will validate use of the probes for diagnosis. Phase II research will also validate their use for monitoring minimal residual disease. In Phase II research, the probes will also be optimized to reduce background hybridization signal. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE